1. Field of the Invention
This invention relates generally to the field of molecular imaging. More specifically, the invention relates to fluorescence optical tomography using patterned illumination.
2. Background of the Invention
Molecular imaging is a rapidly advancing research area with the potential of providing early diagnosis and identification of the human diseases. Optical fluorescence tomography is a novel molecular imaging modality that attempts to recover the spatial distribution of light emitting fluorophores inside a highly scattering medium, such as biological tissue, from measurements made on the surface of the medium. This technique offers many advantages including non-invasiveness and the ability to construct 3D images from 2D measurements. The quantification of a non-uniform quantum yield distribution or fluorophore absorption is of major interest in molecular imaging of biological tissue, especially for cancer applications.
Fluorescence optical tomography is typically performed in a model-based framework, wherein a photon transport model is used to generate predicted surface fluorescence measurements for a given fluorescence absorption map in the interior of a medium. More specifically, the interior image is reconstructed by solving an optimization problem by minimizing the difference between observed surface measurements and surface measurements predicted from a physical model. Because photon propagation in a biological medium is diffuse, the image reconstruction problem can be ill-posed. In other words, very different fluorophore distributions can cause similar surface fluorescence measurement profiles. Thus, the quality and information content of the surface fluorescent measurements is crucial to the recovery of a true and accurate interior image.
Prior research has focused on using multiple fiber optics for delivering excitation light and taking fluorescence measurements at different locations on the tissue boundary. However, fiber optics based tomography systems suffer from sparse measurement data, and inadequate excitation light penetration into the tissue interior. This is because only a finite number of optical fibers can be employed without increasing the data acquisition time. In an attempt to solve this problem, area illumination and detection has been investigated. While area-illumination provides enhanced excitation light penetration, the tomography analysis is complex because of the increased ill-posedness introduced by the availability of only the reflectance measurements.
Consequently, there is a need for a method and system of fluorescence optical tomography which can generate dense data sets and enhanced excitation light penetration. Additional needs include reasonable data acquisition time and computationally efficient solutions to the image reconstruction problem.